[PATCH] D16204: ValueTracking: Use fixed array for assumption exclude set in Query; NFC

[Matthias Braun via llvm-commits]

MatzeB added a comment.

In http://reviews.llvm.org/D16204#327491, @reames wrote:

> Given MaxDepth is less than the Small size specified for the SmallPtrSet, I'm not sure why this is faster?  The only difference I can come up with in the new code vs the old is a) the check for isSmall and b) the fact the insert code is outlined for SmallPtrSet.
>
> I'd really doubt that (a) is the cause.  If it is (b), we should just fix the SmallPtrSet impl to inline the common case of the insertion logic.
>
> Please try measuring with a tweaked version of SmallPtrSet.  Unless you can show that the hand rolled code is still much faster, I'm hesitant to take this change.


In the majority of the cases the set isn't used at all, I didn't see any performance differences when tweaking the insertion/query logic. The gains appear to come from the simplified initialization (and maybe reduced stack usage?).


Repository:
  rL LLVM

http://reviews.llvm.org/D16204